That includes his words about minority groups, which experts and activists say shatter the boundaries of modern political speech.

Those who follow political psychology and civil rights issues say the rhetoric from some conservative figures has become more rigid — and, at times, blatantly racist — since Trump’s campaign gained national traction.

Whether the bombastic billionaire is an unstoppable Pied Piper or a once-in-century genie that soon will be shoved back into the bottle, along with his politically incorrect messages, will be up to voters.

Trump and his supporters say he is not racist, and insist his policy pronouncements are aimed at making the country safer and more economically prosperous.

Longtime GOP operatives, especially ones from the so-called establishment wing of the party, spent most of the last year telling anyone who would listen that such pronouncements meant Trump essentially was disqualifying himself. There was no way he would last much longer as Republicans picked their nominee, they said on countless cable news shows.

But as the real estate mogul-turned-reality show star moved closer and closer to the nomination, he seemed to double down on racially tinged rhetoric .

At campaign rallies, he urged violence against protesters, many of whom were blacks or other minorities. In early June, the nomination essentially secured, he referred to a black man at a stop in California as “my African-American.”

“Look at him!” Trump told those in attendance, pointing at the man. Days later, Speaker Paul D. Ryan, R-Wisc., said Trump uttered a “textbook definition of a racist comment” when he alleged a judge hearing a business case would rule against him because of the jurist’s Mexican heritage.

“Trump’s rhetoric, and the fact he’s been able to continue to succeed without being punished for it seems to have changed the norms of political and public discourse,” said Christopher Federico , a political psychology professor at the University of Minnesota.

“And there’s no question he has changed the norms on public displays of blatant racism,” Federico said. “The other thing that’s happened is he’s become the leader of his political party, with other prominent Republicans falling in to support him. … Research shows people take cues from their political leaders on what they can and cannot say publicly.”

Federico said that Trump's messaging — and what it has unleashed — “is the most serious thing I’ve seen in my lifetime."

“This 'old white people' business does get a little tired, Charlie,” King said on MSNBC. “I'd ask you to go back through history and figure out, where are these contributions that have been made by these other categories of people that you're talking about, where did any other subgroup of people contribute more to civilization?”

The host then chimed in: “Than white people?”

“Than Western civilization itself,” King said. “It's rooted in Western Europe, Eastern Europe and the United States of America and every place where the footprint of Christianity settled the world. That's all of Western civilization.”

To be sure, given the United States’ turbulent and bloody history with race relations, such opinions have been shared among like-minded citizens from the start.

But after the progress of the Civil Rights and other movements, such views, if not eradicated, often were at least not openly expressed.

But King and other white officials who are no longer self-editing on national television feels like the pendulum swinging in the opposite direction.

That’s why African-American activists like Barbara Arnwine , founder of the Transformative Justice Coalition and adjunct professor at Columbia Law School, worry that the United States, touted by conservatives and liberals as a racial melting pot and example to the rest of the world, has hit a new “a low point.”

“We are in a terrible and retrogressive era,” Arnwine said. “Donald Trump’s campaign reminds me too much of clips I’ve seen of George Wallace .”

Like the 1960s Alabama governor and staunch segregationist, Arnwine worries Trump is making it acceptable for whites to publicly express views that mere months ago were politically incorrect.

“Just like Wallace, Trump is the angry white leader who is blaming everybody else for problems that have more to do with global economics than anything here in our country,” she said.

William Galston , a senior fellow at the Brookings Institute who worked for former President Bill Clinton, said the public sees Trump’s rhetoric against political correctness as a “permission slip” to bring what were once private thoughts on controversial topics to the forefront.

Galston said the modern generation has mostly accepted the notion that if one’s private thoughts don’t conform with the public’s general view, they should stay silent. “Trump is saying: Who says?” Galston said.

At the Republican National Convention this week, messages appeared mixed.

Just 18 of the 2,472 delegates, or 0.7 percent, of the delegates are black, according to NBC News.

But Trump was portrayed as someone who wants to be everyone’s president — not just a commander in chief for white America.

There were speakers and benediction-presenters of other races and religions. Several surrogates and family members declared the man they know better than any American wants to unite the country.

But there also were moments when the words and actions of those on stage at the Quicken Loans Arena — and in the audience — were cringe-worthy and deeply troubling for a country with such a troubled history on race.

“He’s been using the coded buzzwords and phrases to signal to that element in America to tap into those bigoted and racist sentiments,” said Ronnie Dunn , a Cleveland State University professor who studies racial issues.

David Clarke , an African-American sheriff from Milwaukee County, Wisc., did mention civil rights icon Martin Luther King, Jr. during his convention speech. But the crowd remained mostly silent.

Each time retired Army Lt. Gen. Michael Flynn and former New York City Mayor Rudolph Giuliani mentioned “killing” terrorists who claim Islam as their religion, “The Q” crowd responded with enthusiasm.

Then there was actor Scott Baio , who looked into the television cameras from the main stage and urged Americans to vote for Trump so the new GOP standard bearer can “make America America again.”

More code words?

“Trump has pulled the scab off of a very deep wound and we’ve just tried to put Band-Aids on it,” Dunn said. “Regardless of who the next president is, we’ll need to examine these issues. But I think a Trump presidency is not capable of that.”

“There and here, you have a group of people that haven’t done that well with changes in our economy,” she said. “Just like in the U.S., there is a feeling that establishment politics aren’t for them. And this new crop of leaders see that and are picking up on it with great success.”